Radiotelegraph system



July 31, 1923. 1,463,386

w. l.. CARLSON E T Al.

RADIO TELEGRAPH SYSTEM Filed April -22 1920 5 Sheets-Sheet l MWI".

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July 31, 15523.

1,463,386 W. L. CARLSON ET AL RADIOy TELEGRAPH SYSTEM Filed April 22,1920 3 Sheets-Sheet 2 Invenow July 31, 1923. 1,463,386

W. L. CARLSON ET AL RADI O TELEGRAPH SYSTEM Filed April 22. 1920 3Sheets-Sheet 3 @www Patented Jury si, i923.

PATENT GFFICE.

WINDELL L. CARLSON AIND EARL C. HANSON, F WASHINGTON, DISTRICT 0l'OOLUIBIA..

i BADIOTELEGBAPH SYSTEM.

Application led April 22,

To all 'whom it may concern:

Be it known that we, WENDELL L. 'CARL- soN and EARL C. Hanson, citizensof tne United States, residing at Washington,

I District of Columbia, have invented certain new and usefulImprovements in Radiotelegraph Systems, of which the following is aspecification.

This invention relates to the reception of l0 radio or wireless signalsand more particularly to those systems employing sustained wavereception. i

The primary object of our invention is to provide an electric circuitfor selectively receiving electric signals.

A further object is to provide an electric circuit for selectivelyrecording electric signals on a permanent recording device andselectively reproducing said recorded signals, so as to actuate aresponsive device. O

The invention is illustrated diagrammatically in two of its forms in theaccompanyin drawings, wherein- Figure 1 shows a receiving ap aratus forzu selectively recording received ra io signals;

and

Figure 2 shows apparatus for selectively re roducing received signals inFigure 1.

igure 3 shows receiving apparatus for sea0 lectively receiving radiosignals.

Referring particularly to the diagram shown in Figure 1 referencecharacter 1 represents a tuned antenna circuit coupled to a tunedsecondary circuit 2. The secondary 85 circuit 2 is connected t0 themultistage high power amplifier comprising the thermionic vacuum tubes3, 5 and 7, the tuned radio frequency transformer 4 having a naturalperiod of approximately the same wave length as the `signal energy to bereceived and the audio frequency transformer 6. Condenser 8 shunted bythe `usual grid leak, is inserted in the grid circuit of the detectortube 5.

The telegraphone recorder 10 comprises the electromagnets 9 and themoving steel wire 11, which is operated by reel mechanism 12. Motor 13drives reel mechanism 12 by means of the extended shaft 14.

The vacuum tube generator 18 is loosely coupled to the tuned circuit 2.

In Figure 2 the electromagnets 9 are connected to the input of anamplifier comprising tuned audio frequency transformer 15 1920. SerialNo. $75,688.

designed for maximum efficiency at the particular frequency employed andthermionic tube 16. The output of the amplifier is connected to an audiofrequency responsive device 17.

In Figure 3 the audio-radio frequency amplifier shown in Figure 1 hasits output connected to the electromagnets 19, which partially surroundmagnetic rotor 21. Electromagnets 22 are connected through audiofrequency transformer 15 to vacuum tube 16. The output of vacuum tube 16is connected to the signal responsive device 17. The electromagnets 23are energizedby the batterv 24.

The operation of the system is as follows: The radio frequency circuits1 and 2, Figure 1, are definitely tuned to the frequency of the incomingradio si nal. The thermionic vacuum tube 2 amp ies the received radiofrequency energy and imprees said energy on the grid circuit of thedetector tube 5 through the radio fre uency transformer 4. The energyfrom tlie oscillating tube generator 18 is also impressed on the gridcircuit 0f the detector tube 5. Said oscillating energy is of afrequency differing by 500 cycles from the frequency of the incomingsignal. The resulting heterodyne b'eat of 500 cycles is transferred tothe audio frequency amplifying tube 7, by means of the audio frequencytransformer 6. The output energy of the vacuum tube 7 energizes aplurality of electromagnets 9, which are arranged in a row along thepath of the moving steel wire 11.

The individual sets of windings function similar to the well knowntalking heads in the usual telegraphone.

One of the important, factors to be considered in this invention is tohave the physical distance between adjacent electromagnets equal to, orin multiple of the physical distance between magnetic stresses appliedto the moving steel wire by the action of the incoming signal. Thepolarity of adjacent electromagnets must be alternately reversed if theyare to act on the moving steel wire at distances from each other,corresponding to 1%, 2%, etc. cycles. (Considerin cycle as correspondingto the linear lengt of localized charge, placed on the wire by cycleincoming audio frequency currentl The polarity of the electromagnetsshown in the drawing are indicated to agree with the above condition.

The polarity of adjacent electromagnets must be identical if they are toact on the moving steel wire at distances from each other correspondingto 1, 2, 3 and etc. cycles.

The linear dimensions of the space magnetic stress develo ed on thesteel wire, will be determined by t e frequency of the signal recordedand the speed of the steel wire. For example, if the beat si nal to berecorded is adjusted to 500 cyc es and the steel Wire is moving at therate of 125 inches per second, then the ad'jacent electromagnets must bephysically adjusted so. that their magnetic fields will act on the wireat space distances of i, il, etc. inches from each other, depending onthe polarity of adjacent electromagnets and the physical limitations ofthe electromagnet construction.

Any arrangement of electromagnets may be employed, which will allow forthe synchronizin 0f the three variable factors mentione above, namely,1st, frequency of the signal which it is desired to record, 2nd,distance between adjacent electromagnets and 3rd, linear speed of themoving element on which the signal is to be recorded.

It will be understood that if an interfering signal of, for example, 800cycles is impressed on the electromagnets, that the phase relation ofthe various factors will not permit the signal energy localized on thesteel wire by one set of clectromagnets, to synchronize with theelectromagnetic field produced by the adjacent set of electromagnets,when said localized signal energy passes under the influence of the saidadjacent electromagnets. A decrease in strength of signal recorded will,therefore, result.

A 500 cycle signal, for which the apparatus is adjusted to receive, willbe recorded with increased intensity, because each set of electromagnetswill strengthen the localized signal energy on the steel wire as itmoves in synchronism past adjacent electromagnetic fields.

In the practical operation of the apparatus, the elcctromagnets may bedesigned to have either open or closed magnetic iron cores. Successiveelectromagnets may, if desired, be designed to have a decreasingmagnetic effect on the steel wire by employing a fewer number of turnsof wire, or by lengthening the air gap in the iron core.

In order that the speed of the moving steel wire may remain constant,any suitable means may be employed for automatically regulating thespeed of the driving motor to compensate for the constantly varyingdiameter of the reels 12, due to the unreeling of the steel wire woundthereon.

To eliminate inductive interference, caused by the driving motor 13, itis advantageous to place the drivin motor a few feet away from thetelegrap one apparatus and connect by shaft.

In Fi ure 2 the reproducing process is the reverse uplication of therecording process in so far as the telegraphone apparatus is concerned.Additional selectivity being obtained as in the recordin process. Thecycle signal energy, derived from the telegraphone, actuates the audiofrequency re ceiving device 17, by means of the vacuum tube amplifiercircuit, comprising the audio frequency transformer 15 and thermionicvacuum tube 16.

In Figure 3 the signal energy impressed on the electromagnets 19 isderived from a source similar to that previously described in Figure 1.

The local external oscillating vacuum tube enerator 18 of Figure 1, isnot shown in `igure 3, but may be employed, if the radio frequencycircuit including tube 3 is not adjusted to produce local oscillationsto autodyne with the incoming signal producing the required audio beatnote.

The rotating disc 21 in Figure 3, is substituted for the moving steelwire l1 in the telegraphone 10, shown in Figures 1 and 2. The signalenergy is recorded on the rotating disc 21 and as the disc rotates pastthe electromagnets 22, the localized energy recorded on the disc 21actuates the electromagnets 22 in a manner similar to the processwherein the energy on the steel wire in Figure 2 actuates theelectromagnets 9. 100 The 4responsive device 17, in Figure 3, iseventually acted upon in like manner to the process of actuating theresponsive device 17 in Figure 2.

The electromagnets 23, energized by the 105 battery 24, are employed toerase the localized magnetic signal energy recorded on the revolvingdisc 21, after said disc has passed the electromagnets 22. The rotatingdisc may be constructed of laminated steel.

It will be understood that we are not to be restricted to the specificstructure of the apparatus shown herein.

What we claim is:

1. In a system of radio telegraphic recep- 115 tion means for receivingsignals of a predetermined frequenc a telegraphone, a re cording elementt erefor, a. plurality of electromagnets associated therewith and spacedapart in proportion to the frequency 12" of the signals to be receivedand the linear speed of the recording element.

2.. In a system of radio telegraphic reception means for selectivelyreceiving energy of a. particular frequency comprising a 125 teegraphone having a recording element, a multiple set of magnetsassociated therewith and connected in the receiving circuit, saidmagnets being spaced apart in proportion to the frequency of the signalsto be ren" ceived, and the linear speed of the recording element.

3. In a system of radio telegraphic reception means for selectivelyreceiving energy A of a articular frequency comprising a telegrap onehaving a recording element, a plu` rality of magnets connected in seriesand arranged to be synchronousl energized by the received energ in accorance with the speed of the recor ing element, the spacin of said magnetsand the frequency of sai signal, and a reproducing circuit for selectivetranslation of the recorded signals.

4. In a system of radio telegraphic reception the combination of acircuit adjusted to respond to signals of a definite audio freuency atele aphone having a recording' e ement whichgi; unwound from one reelan continuously stored in bulk on another reel and means 1n said circuitfor integrating en- 20 raphone wire elementl a circuit energized al ythe received signals including a plurality of sets of multiple electromagnets received in series and adjusted in relation to said wire elementto respond to the frequency of said signals.

WENDELL L. CARLSON. EARL C. HANSON.

